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Despite their potential significance for later linguistic outcomes, early aspects of vocalization had been seriously undervalued in the past, and thus, minimally investigated until relatively recently. The present article sets out to critically examine existing evidence to: i) ascertain whether vocalization frequency (volubility) posits a plausible marker of cochlear implantation success in infancy, and ii) determine the clinical usefulness of post-implementation vocalization frequency data in predicting later language development. Only recent peer-reviewed articles with substantial impact on vocalization growth during the first year of life, examining sound production characteristics of normally hearing (NH) and hearing impaired infants fitted with cochlear implantation (CI) were mentioned. Recorded differences in linguistic performance among NH and CI infants are typically attributed to auditory deprivation. Infants who have undergone late CI, produce fewer syllables (low volubility) and exhibit late-onset babbling, especially those who received their CIs at the age of 12 months or thereafter. Contrarily, early recipients (before the 12-month of age) exhibit higher volubility (more vocalizations), triggered from CI-initiated auditory feedback. In other words, early CI provides infants with early auditory access to speech sounds, leading to advanced forms of babbling and increased post-implementation vocalization frequency. Current findings suggest vocalization frequency as a plausible criterion of the success of early CI. It is argued that vocalization frequency predicts language development and affects habilitation therapy.

One-pot, sequential reversible addition−fragmentation chain transfer (RAFT) polymerization was employed for the preparation of five end-linked semifluorinated amphiphilic polymer conetworks based on 2,2,2-trifluoroethyl methacrylate (TFEMA, hydrophobic monomer) and 2-(dimethylamino)ethyl methacrylate (DMAEMA, hydrophilic monomer). 1,4-Bis[2-(thiobenzoylthio)prop-2-yl]benzene (1,4-BTBTPB) was used as the chain transfer agent, while ethylene glycol dimethacrylate (EGDMA) served as the cross-linker. Three of the end-linked conetworks were based on ABA triblock copolymers with polyDMAEMA midblocks with degrees of polymerization (DPs) of 50 and polyTFEMA end-blocks with overall polyTFEMA DPs of 25, 50, and 75. The fourth end-linked amphiphilic polymer conetwork was based on an equimolar BAB triblock copolymer with a polyTFEMA midblock and an overall copolymer DP of 100. The last end-linked conetwork was based on a statistical copolymer. A randomly cross-linked conetwork was also prepared by the simultaneous terpolymerization of the two comonomers (equimolar) and the cross-linker. The molecular weights and compositions of all the polymer precursors to the conetworks were characterized using gel permeation chromatography and 1H NMR spectroscopy, respectively. The conetworks were characterized in terms of their degrees of swelling (DS) in THF and in water as a function of the solution pH. All conetworks swelled more in acidic than in pure water due to the ionization of the DMAEMA units in acidic water. The low pH aqueous DS of the statistical copolymer-based end-linked conetwork was higher than those of its triblock copolymer counterparts due to lack of microphase separation within the former conetwork. Finally, the microphase separation of the amphiphilic conetworks in deuterium oxide was investigated using small-angle neutron scattering which indicated a distance between the hydrophobic scattering centers of about 15 nm. [ABSTRACT FROM AUTHOR]

The structural responses of a polymer−clay nanocomposite hydrogel to an imposed shear field are investigated from the nanometer to the micrometer length scales. The effects of polymer molecular weight and concentration of the components are probed, and the structural response of the individual components is explored using contrast matching techniques with small-angle neutron scattering. At rest the clay structure appears minimally perturbed by the presence of the polymer. As the network begins to be disrupted under the effect of low shear, large-scale inhomogeneities roll up and orient with their long axis parallel to the neutral direction. With increasing shear rates the effect of the polymer−clay interactions becomes apparent with nanoscopic orientation of both the clay platelets and the polymer chains, but only in systems where polymer bridging of the clay can occur. The clay and polymer concentration dependence of the shear response suggests an ideal combination of concentrations and polymer molecular weights with implications for materials design. [ABSTRACT FROM AUTHOR]

Degradable amphiphilic conetworks, based on end-linked amphiphilic ABA triblock copolymers with a labile fragment in the middle, were synthesized by sequential group transfer polymerization (GTP) of monomers and cross-linker, using a GTP bifunctional initiator containing two hemiacetal ester cleavable groups. The degrees of swelling (DSs) in tetrahydrofuran (a nonselective solvent) of most conetworks span a range of values from 15 to 18, whereas the sol fraction ranged between 27 and 42% in most cases. The labile groups of the initiator fragment allowed for the facile, site-specific conetwork cleavage in pure water and alcohols at a rate that depended on polymer architecture and composition. A systematic investigation was performed by following in detail the temporal evolution of the swollen mass of the conetworks in water and methanol. Most interestingly, a particular conetwork presented a maximum in its swelling profile with time both in water (DSmax∼ 20) and in methanol (DSmax∼ 30) due to the simultaneous occurrence of swelling and degradation. A small-angle neutron scattering (SANS) study of the conetworks in deuterated water enabled the independent monitoring of conetwork swelling and degradation as these two processes appeared as two separate peaks in the SANS profiles, the former of which being related to the self-organization of the hydrophobic blocks within the conetworks, whereas the latter being connected with the correlations among the amphiphilic star block copolymers released in solution during the course of conetwork hydrolysis. [ABSTRACT FROM AUTHOR]

We investigate the influence of ionic strength on the structural heterogeneity and viscoelastic properties of nanocomposite hydrogels. We use small-angle scattering and rheology to monitor structural changes as a function of ionic strength. Increasing ionic strength makes the nanocomposite gels macroscopically heterogeneous, stiffer and more turbid. At high shear rates, nanometre structures rearrange within aggregates and orient in the flow direction. The changing structural properties that develop with ionic strength are due to increased heterogeneity of nanoparticle distribution and polymer–nanoparticle interactions as well as to the formation of PEO [poly(ethylene oxide)] aggregates interacting with sodium cations, which reinforce the overall hydrogel network. [ABSTRACT FROM AUTHOR]